Multiplexors under an array of memory cells

ABSTRACT

A sense amplifier can be formed outside of/horizontally adjacent to an array of vertically stacked tiers of memory cells. Memory cells can be sensed via multiplexors formed under the array that can operate to couple vertical sense lines (to which the memory cells are coupled) to horizontal sense lines (to which the sense amplifier is coupled).

TECHNICAL FIELD

The present disclosure relates generally to memory devices, and moreparticularly, to multiplexors under an array of memory cells.

BACKGROUND

Memory is often implemented in electronic systems, such as computers,cell phones, hand-held devices, etc. There are many different types ofmemory, including volatile and non-volatile memory. Volatile memory mayrequire power to maintain its data and may include random-access memory(RAM), dynamic random-access memory (DRAM), static random-access memory(SRAM), and synchronous dynamic random-access memory (SDRAM).Non-volatile memory may provide persistent data by retaining stored datawhen not powered and may include NAND flash memory, NOR flash memory,nitride read only memory (NROM), phase-change memory (e.g., phase-changerandom access memory), resistive memory (e.g., resistive random-accessmemory, cross-point memory), ferroelectric random-access memory (FeRAM),or the like.

As design rules shrink, less semiconductor space is available tofabricate memory, including DRAM arrays. A respective memory cell forDRAM may include an access device (e.g., a transistor) having first andsecond source/drain regions separated by a channel region. A gate mayoppose the channel region and be separated therefrom by a gatedielectric. An access line, which is sometimes referred to in the art asa word line, is electrically connected to the gate of the DRAM cell. ADRAM cell can include a storage node, such as a capacitor cell, coupledby the access device to a sense line, which is sometimes referred to inthe art as a digit line. The access device can be activated (e.g., toselect the cell) by an access line coupled to the access transistor. Thecapacitor can store a charge corresponding to a data value of arespective cell (e.g., a logic “1” or “0”).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a portion of a vertical threedimensional (3D) memory in accordance a number of embodiments of thepresent disclosure.

FIG. 2A is a first plane view of a portion of a 3D memory in accordancea number of embodiments of the present disclosure.

FIG. 2B is a second plane view of a portion of a 3D memory in accordancea number of embodiments of the present disclosure.

FIG. 2C is a third plane view of a portion of a 3D memory in accordancea number of embodiments of the present disclosure.

FIG. 3 is a top-down view of a portion of a vertical 3D memory inaccordance a number of embodiments of the present disclosure.

FIG. 4 is a diagram of a portion of a vertical 3D memory in accordance anumber of embodiments of the present disclosure.

FIG. 5 is a schematic illustration of a vertical sense line multiplexorin accordance a number of embodiments of the present disclosure.

FIG. 6 is a block diagram of an apparatus in accordance with a number ofembodiments of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure describe multiplexors under anarray of memory cells. A vertical three-dimensional (3D) memory (e.g.,3D-DRAM) in accordance a number of embodiments of the present disclosurecan include an array of memory cells made up of vertically stacked tiersof memory cells. The memory cells are controlled and/or accessed viavertical sense lines running through the tiers of memory cells andhorizontal access lines running within respective tiers of memory cells.The horizontal access lines can be coupled to a number of access linedrivers via staircase connection, thereby providing power to subsets ofthe vertical sense lines via the respective horizontal access line. Thevertical sense lines can be coupled to respective horizontal sense linesthat are formed under the array. The horizontal sense lines can becoupled to respective sense amplifiers outside of the array. Thevertical sense lines can each be coupled to the respective horizontalsense line via a respective multiplexor, which allows individualvertical sense lines to be activated and/or deactivated for reading andwriting operations, among other operations.

Embodiments of the present disclosure provide for simplified circuitryformed under an array of memory cells (e.g., an array of verticallystacked tiers of memory cells). In at least one embodiment, thecircuitry formed under the array can be simplified by not includingsense amplifiers, which can instead be located outside of the arrayand/or horizontally adjacent to the array. Such simplified circuitry canoccupy less space under the array, which will make more vertical spacesavailable for forming memory cells within the array. Therefore, theembodiments of the present disclosure can increase cell storage densityof the array of vertically stacked tiers of memory cells (e.g., aquantity of memory cells within a particular space/volume).

As used herein, the singular forms “a”, “an”, and “the” include singularand plural referents unless the content clearly dictates otherwise.Furthermore, the word “may” is used throughout this application in apermissive sense (i.e., having the potential to, being able to), not ina mandatory sense (i.e., must). The term “include,” and derivationsthereof, mean “including, but not limited to.” The term “coupled” meansdirectly or indirectly connected.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 103 may referenceelement “03” in FIG. 1, and a similar element may be referenced as 203in FIG. 2. Analogous elements within a Figure may be referenced with ahyphen and extra numeral or letter. Such analogous elements may begenerally referenced without the hyphen and extra numeral or letter. Forexample, elements 103-1, 103-2, 103-A in FIG. 1 may be collectivelyreferenced as 103. As used herein, the designators “A”, “B”, “Q”, “P”,and “N”, particularly with respect to reference numerals in thedrawings, indicates that a number of the particular feature sodesignated can be included. As will be appreciated, elements shown inthe various embodiments herein can be added, exchanged, and/oreliminated so as to provide a number of additional embodiments of thepresent disclosure. In addition, as will be appreciated, the proportionand the relative scale of the elements provided in the figures areintended to illustrate certain embodiments of the present invention andshould not be taken in a limiting sense.

FIG. 1 is a schematic illustration of a portion of a vertical 3D memoryin accordance a number of embodiments of the present disclosure. FIG. 1illustrates a circuit diagram showing a cell array of a portion of a 3Dsemiconductor memory device according to embodiments of the presentdisclosure. FIG. 1 illustrates a cell array may have a plurality of subcell arrays 101-1, 101-2, . . . , 101-N. The sub cell arrays 101-1,101-2, . . . , 101-N may have various configurations. For instance, thesub cell arrays 101-1, 101-2, . . . , 101-N may be arranged along asecond direction (D2) 105. Each of the sub cell arrays 101-2 may includea plurality of access lines 107-1, 107-2, . . . , 107-B (which also maybe referred to word lines). Also, each of the sub cell arrays 101-2 mayinclude a plurality of sense lines 103-1, 103-2, . . . , 103-A (whichalso may be referred to as bit lines, data lines, or digit lines). InFIG. 1, the access lines 107-1, 107-2, . . . , 107-B are illustratedextending in a first direction (D1) 109 and the sense lines 103-1,103-2, . . . , 103-A are illustrated extending in a third direction (D3)111; however, embodiments are not so limited. The first direction (D1)109 and the second direction (D2) 105 may be considered in a horizontal(“X-Y”) plane. The third direction (D3) 111 may be considered in avertical (“Z”) plane. Hence, according to a number of embodimentsdescribed herein and as illustrated in FIG. 1, the sense lines 103-1,103-2, . . . , 103-A are extending in a vertical direction (the thirddirection (D3) 111); however, embodiments are not so limited. Forinstance, according to a number of embodiments described herein thesense lines 103-1, 103-2, . . . , 103-A may extend in a horizontaldirection (direction (D1) 109).

As mentioned, embodiments are not limited to the schematic illustrationof FIG. 1. One or more embodiments provide that the sense lines 103-1,103-2, . . . , 103-A may extend in the first direction (D1) 109 and theaccess lines 107-1, 107-2, . . . , 107-B may extend in the thirddirection (D3) 111. As such, one or more embodiments provide that thesense lines 103-1, 103-2, . . . , 103-A may extend in a horizontaldirection and that the access lines 107-1, 107-2, . . . , 107-B extendin a vertical direction.

A memory cell 110 may include an access device (e.g., transistor) and astorage node located at an intersection of each access line 107-1,107-2, . . . , 107-B and each sense line 103-1, 103-2, . . . , 103-A.Memory cells may be written to, or read from, using the access lines107-1, 107-2, . . . , 107-B and sense lines 103-1, 103-2, . . . , 103-A.As shown in FIG. 1, the access lines 107-1, 107-2, . . . , 107-B mayconductively interconnect memory cells along horizontal rows of each subcell array 101-, 101-2, . . . , 101-N, and the sense lines 103-1, 103-2,. . . , 103-A may conductively interconnect memory cells along verticalcolumns of each sub cell array 101-, 101-2, . . . , 101-N. One memorycell 110 may be located between one access line 107-2 and one sense line103-2. Each memory cell may be uniquely addressed through a combinationof an access line 107-1, 107-2, . . . , 107-B and a sense line 103-1,103-2, . . . , 103-A.

The access lines 107-1, 107-2, . . . , 107-B may be or includeconducting patterns (e.g., metal lines) disposed on and spaced apartfrom a substrate. As shown in FIG. 1, the access lines 107-1, 107-2, . .. , 107-B may extend in a first direction (D1) 109. The access lines107-1, 107-2, . . . , 107-B in one sub cell array 101-2, may be spacedapart from each other in a vertical direction (the third direction (D3)111). However, embodiments are not limited as such.

The sense lines 103-1, 103-2, . . . , 103-A may be or include conductivepatterns (e.g., metal lines) extending in a vertical direction, as shownin FIG. 1, with respect to the substrate (the third direction (D3) 111).The sense lines in one sub cell array 101-2, may be spaced apart fromeach other in the first direction (D1) 109. However, embodiments are notlimited as such.

A gate of a memory cell 110 may be connected to an access line 107-2,and a first conductive node (e.g., first source/drain region) of anaccess device (e.g., transistor) of the memory cell 110 may be connectedto a sense line 103-2. Each of the memory cells 110 may be connected toa storage node (e.g., capacitor). A second conductive node (e.g., secondsource/drain region) of the access device (e.g., transistor) of thememory cell 110 may be connected to the storage node (e.g., capacitor).While first and second source/drain region reference are used herein todenote two separate and distinct source/drain regions, it is notintended that the source/drain region referred to as the “first” and/or“second” source/drain regions have some unique meaning. It is intendedonly that one of the source/drain regions is connected to a sense line103-2 and the other may be connected to a storage node.

FIG. 2A is a first view of a portion of a 3D memory in accordance anumber of embodiments of the present disclosure. The view in FIG. 2Ashows a a portion of the 3D memory including a cross-section view of abottom portion of the 3D memory including horizontal sense lines 222 andsense amplifiers 226 as well as a cross-section view of another bottomportion of the 3D memory including memory cells 210 and horizontalaccess lines 207. The portion of the 3D memory illustrated in FIG. 2A inthe first direction 209 (D1) and the second direction 205 (D2) that arecorresponding to the first direction 109 (D1) and the second direction105 (D2), respectively, as illustrated in connection with FIG. 1.

FIG. 2A illustrates memory cells 210 respectively coupled to horizontalaccess lines 207. For example, the memory cells 210-1, 210-2, 210-3,210-4 are coupled to the horizontal access line 207-1; the memory cells210-5, 210-6, 210-7, 210-8 are coupled to the horizontal access line207-2; the memory cells 210-9, 210-10, 210-11, 210-12 are coupled to thehorizontal access line 207-3; and the memory cells 210-13, 210-14,210-15, 210-16 are coupled to the horizontal access line 207-4. FIG. 2Aillustrates pairs of horizontal sense lines 222 respectively coupled tosense amplifiers 226, which are formed outside of an array of verticallystacked tiers of memory cells (and/or located horizontally adjacent tothe array). For example, the pair of horizontal sense lines 222-1(horizontal sense lines 222-1-1 and 222-1-2) is coupled to the senseamplifier 226-1; the pair of horizontal sense lines 222-2 (horizontalsense lines 222-2-1 and 222-2-2) is coupled to the sense amplifier226-2; the pair of horizontal sense lines 222-3 (horizontal sense lines222-3-1 and 222-3-2) is coupled to the sense amplifier 226-3; and thepair of horizontal sense lines 222-4 (horizontal sense lines 222-4-1 and222-4-2) is coupled to the sense amplifier 226-4.

Further, the memory cells 210 are coupled to the horizontal sense lines222 via respective multiplexers 232. For example, the memory cells 210-4and 210-12 are coupled to the horizontal sense lines 222-1-1 viamultiplexors 232-1 and 232-3, respectively; the memory cells 210-8 and210-16 are coupled to the horizontal sense lines 222-1-2 viamultiplexors 232-2 and 232-4, respectively; the memory cells 210-3 and210-11 are coupled to the horizontal sense lines 222-2-1 viamultiplexors 232-11 and 232-5, respectively; the memory cells 210-7 and210-15 are coupled to the horizontal sense lines 222-2-2 viamultiplexors 232-12 and 232-6, respectively; the memory cells 210-2 and210-10 are coupled to the horizontal sense lines 222-3-1 viamultiplexors 232-13 and 232-7, respectively; the memory cells 210-6 and210-14 are coupled to the horizontal sense lines 222-3-2 viamultiplexors 232-14 and 232-8, respectively; the memory cells 210-1 and210-9 are coupled to the horizontal sense lines 222-4-1 via multiplexors232-15 and 232-9, respectively; and the memory cells 210-5 and 210-13are coupled to the horizontal sense lines 222-4-2 via multiplexors232-16 and 232-10, respectively.

Each horizontal access line 207 is coupled to a respective horizontalaccess line driver 228, which may be referred to in the art as asub-word line driver. Although shown as a single element, the horizontalaccess line driver 228 can include multiple horizontal access linedrivers and each one of the drivers can be coupled to a respectivehorizontal access line 207. The horizontal access line drivers 228 canbe coupled to a power supply, such as a positive power supply.

As further illustrated in FIG. 2A, the horizontal access lines extend ina direction 209 (D1) and pairs of horizontal sense lines 222 extend in adirection 205 (D2). Although not shown in FIG. 2A (but shown in FIG. 2Band FIG. 2C), the pairs of horizontal sense lines 222 are furtherrespectively coupled to vertical sense lines 203, which extend in adirection 211.

FIG. 2B is a second plane view of a portion of a 3D memory in accordancea number of embodiments of the present disclosure. The plane view inFIG. 2B shows a cross-section of a portion of the 3D memory in the thirddirection 211 (D3) and the second direction 205 (D2) that arecorresponding to the third direction 111 (D1) and the second direction105 (D2), respectively, as illustrated in connection with FIG. 1.

As illustrated in FIG. 2B, vertically stacked memory cells 210 arerespectively coupled to vertical sense lines 203-1 to 203-4. Forexample, memory cells including the memory cell 210-4 (and those memorycells stacked vertically on the memory cell 210-4) are coupled to thevertical sense line 203-1; memory cells including the memory cell 210-8(and those memory cells stacked vertically on the memory cell 210-8) arecoupled to the vertical sense line 203-2; memory cells including thememory cell 210-12 (and those memory cells stacked vertically on thememory cell 210-12) are coupled to the vertical sense line 203-3; andmemory cells including the memory cell 210-16 (and those memory cellsstacked vertically on the memory cell 210-16) are coupled to thevertical sense line 203-4.

As further illustrated in FIG. 2B, the memory cells 210 are coupled torespective horizontal access lines 207. For example, the memory cells210-4, 210-8, 210-12, and 210-16 are coupled to the horizontal accesslines 207-1, 207-2, 207-3, and 207-4, respectively.

FIG. 2B further illustrates multiplexors 232 that are coupled to arespective pair of horizontal sense lines and formed under the array ofvertically stacked memory cells. As illustrated in FIG. 2B, themultiplexors 232-1 to 232-3 are coupled to the horizontal sense line222-1-1 (analogous to the horizontal sense line 222-1-1 illustrated inFIG. 2A). Although not illustrated in detail in FIG. 2B, themultiplexors 232-2 and 232-4 are coupled to a different one of the pair,such as the horizontal sense line 222-1-2. Further, the multiplexors232-1, 232-2, 232-3, and 232-4 are coupled to vertical sense lines203-1, 203-2, 203-3, and 203-4, respectively. The control circuitry(e.g., control circuitry 652 illustrated in FIG. 6) can cause themultiplexors 232 to electrically couple/decouple vertical sense lines203 to/from respective horizontal sense lines 222. For example, themultiplexors 232-1 and 232-3 can operate to electrically couple/decouplevertical sense lines 203-1 and 203-3 to/from the horizontal sense line222-1-1.

FIG. 2C is a third plane view of a portion of a 3D memory in accordancea number of embodiments of the present disclosure. The plane view inFIG. 2C shows a cross-section of a portion of the 3D memory in the thirddirection 211 (D3) and the first direction 209 (D1) that arecorresponding to the third direction 111 (D3) and the first direction109 (D1), respectively, as illustrated in connection with FIG. 1.

As illustrated in FIG. 2C, vertically stacked memory cells 210 arerespectively coupled to the horizontal access line 207 and verticalsense lines 203. For example, memory cells 210-12, 210-11, 210-10, and210-9 (and those memory cells stacked vertically on the memory cells210-12, 210-11, 210-10, and 210-9) are coupled to one of the horizontalaccess lines (e.g., the horizontal access line 207-3) and to thevertical sense lines 203-3, 203-5, 203-7, and 203-9, respectively.Further, for example, memory cells 210-16, 210-15, 210-14, and 210-13(and those memory cells stacked vertically on the memory cells 210-16,210-15, 210-14, and 210-13) are coupled to the horizontal access line207-4 and to the vertical sense lines 203-4, 203-6, 203-8, and 203-10,respectively. As further illustrated in FIG. 2C, the horizontal accesslines 207 (including horizontal access line 207-4 and those horizontalaccess lines vertically stacked on the horizontal access line 207-4) andthe horizontal access line driver 228 are coupled via staircaseconnection 215.

Further, as illustrated in FIG. 2C, the vertical sense lines 203-3 to203-10 are respectively coupled to multiplexors 232-3, 232-4, 232-5,232-6, 232-7, 232-8, 232-9, and 232-10. For example, the vertical senselines 203-3 and 204-4 are coupled to the multiplexors 232-3 and 232-4,respectively; the vertical sense lines 203-5 and 203-6 are coupled tothe multiplexors 232-5 and 232-6, respectively; the vertical sense lines203-7 and 203-8 are coupled to the multiplexors 232-7 and 232-8,respectively; and the vertical sense lines 203-9 and 203-10 are coupledto the multiplexors 232-9 and 232-10, respectively.

Each multiplexor can operate to couple/decouple a vertical sense line203 to a respective horizontal sense line 222. For example, themultiplexor 232-3 operates to couple/decouple the vertical sense line203-3 to/from one of the pair of horizontal sense lines 222-1-1; themultiplexor 232-4 operates to couple/decouple the vertical sense line203-4 to/from another one of the pair of horizontal sense lines 222-1-2;the multiplexor 232-5 operates to couple/decouple the vertical senseline 203-5 to/from one of the pair of horizontal sense lines 222-2-1;the multiplexor 232-6 operates to couple/decouple the vertical senseline 203-6 to/from another one of the pair of horizontal sense lines222-2-2; the multiplexor 232-7 operates to couple/decouple the verticalsense line 203-7 to/from one of the pair of horizontal sense lines222-3-1; the multiplexor 232-8 operates to couple/decouple the verticalsense line 203-8 to/from another one of the pair of horizontal senselines 222-3-2; the multiplexor 232-9 operates to couple/decouple thevertical sense line 203-9 to/from one of the pair of horizontal senselines 222-4-1; and the multiplexor 232-10 operates to couple/decouplethe vertical sense line 203-10 to/from another one of the pair ofhorizontal sense lines 222-4-2.

FIG. 3 is a top-down view of a portion of a vertical 3D memory 321 inaccordance a number of embodiments of the present disclosure. Memorycells 310 illustrated in FIG. 3 represent memory cells that are locatedon a same tier (e.g., one of the tiers 430 illustrated in connectionwith FIG. 4).

Memory cells 310 illustrated in FIG. 3 are respectively coupled tovertical sense lines 303. For example, memory cells 310-1, 310-2, 310-3,and 310-4 are respectively coupled to vertical sense lines 303-1, 303-2,303-3, and 303-4, which are further coupled to multiplexors 332-1,332-2, 332-3, and 332-4, respectively. Although not illustrated in FIG.3, the memory cells 310-1, 310-2, 310-3, and 310-4 are coupled to a samehorizontal access line 307. Memory cells 310 that are coupled to a samehorizontal access line 307 can be accessed together as a unit. Forexample, the control circuitry (e.g., control circuitry 652 illustratedin FIG. 6) can cause multiplexors 332-1 to 332-4 to electrically couplerespective vertical sense lines (to which memory cells 310-1 to 310-4are coupled) to one of each pair of horizontal sense lines, such ashorizontal sense lines 322-1-1, 322-2-1, 322-3-1, and 322-4-1 to allowaccess to the memory cells 310-1 to 310-4.

As further illustrated in FIG. 3, each pair of horizontal sense lines322 is coupled to a respective sense amplifier 326, which is formedoutside of an array of vertically stacked tiers of memory cells (and/orlocated horizontally adjacent to the array). For example, the pair ofhorizontal sense lines 322-1-1 and 322-1-2 is coupled to the senseamplifier 326-1; the pair of horizontal sense lines 322-2-1 and 322-2-2is coupled to the sense amplifier 326-2; the pair of horizontal senselines 322-3-1 and 322-3-2 is coupled to the sense amplifier 326-3; andthe pair of horizontal sense lines 322-4-1 and 322-4-2 is coupled to thesense amplifier 326-4. The sense amplifiers 326 can be differentialsense amplifiers and configured to measure (to sense data states ofmemory cells) as a differential voltage between two horizontal senselines of the respective pair. For example, to sense a data state of thememory cell 310-1, the control circuitry (e.g., the control circuitry652 illustrated in FIG. 6) can cause multiplexors 332-1 and 332-5 toelectrically couple vertical sense lines 303-1 and 303-5 to thehorizontal sense lines 322-1-1 and 322-1-2, respectively, activate anaccess line driver coupled to the memory cell 310-1, and cause the senseamplifier 326-1 to sense a differential voltage between the horizontalsense lines 322-1-1 and 322-1-2. Further details of how sense amplifiers326 and multiplexors 332 operate in relation to horizontal sense lines322 are described in connection with FIG. 4.

Although embodiments are not so limited, vertical sense lines, such asvertical sense lines 303, can be spaced apart from one another by aparticular distance, such as 695 nanometers (nm). Further, horizontalsense lines of each pair can be spaced apart from each other by aparticular size, such as 60 nm, and one pair of horizontal sense linescan be spaced part from a different pair of horizontal sense lines by 60nm, although embodiments are not so limited.

The sense amplifiers 326 can be coupled to either one of two ends ofpairs of horizontal sense lines 322. For example, sense amplifiers 326-1and 326-3 are coupled to one end of pairs of horizontal sense lines322-1 and 322-3, respectively, while sense amplifiers 326-2 and 326-4are coupled to an opposite end of pairs of horizontal sense lines 322-2and 322-4, respectively, as illustrated in FIG. 3. Although embodimentsare not so limited, a sense amplifier, such as at least one of the senseamplifiers 336, can run by 4.6 micrometers (μm) in the D2 direction(e.g., the second direction (D2) 205 as illustrated in FIG. 2B) and by 1μm in the D1 direction (e.g., the first direction (D1) 209 asillustrated in FIG. 2A). Although not shown in FIG. 3, access linedrivers can be coupled to either one of two ends of each one of thehorizontal access lines 307, as well.

FIG. 4 is a diagram of a portion of a vertical 3D memory in accordance anumber of embodiments of the present disclosure. The vertical 3D memoryillustrated in FIG. 4 is analogous to that illustrated in FIGS. 1-3, butshown from a different perspective and with a different level of detail.A portion of a plurality of vertically stacked tiers 430-1, 430-2, . . ., 430-P of memory cells in an array are illustrated. The tiers 430 arestacked vertically in the third direction 411 (D3). Also running throughthe tiers 430 in the third direction 411 (D3) are a plurality ofvertical sense lines, such as vertical sense lines 403-1 to 403-8. Eachvertical sense line 403 is coupled to one memory cell 410 in each tier430.

Each tier 430-1, 430-2, . . . , 430-P can include memory cells coupledto respective horizontal access lines that that each run along the firstdirection 409 (D1) in parallel to each other. As an example, asillustrated in FIG. 4, a tier 430-1 includes memory cells 410-1 and410-5 (coupled to a horizontal access line 407-1 and vertical senselines 403-1 and 403-5, respectively), and memory cells 410-2 and 410-6(coupled to a horizontal access line 407-2 and vertical sense lines403-2 and 403-6, respectively), memory cells 410-3 and 410-7 (coupled toa horizontal access line 407-3 and vertical sense lines 403-3 and 403-7,respectively), and memory cells 410-4 and 410-8 (coupled to a horizontalaccess line 407-4 and vertical sense lines 403-4 and 403-8,respectively). Similarly, a tier 430-2 can include memory cells 410-9and 410-13 (coupled to a same horizontal access line and vertical senselines 403-1 and 403-5, respectively), 410-10 and 410-14 (coupled to asame horizontal access line and vertical sense lines 403-2 and 403-6,respectively), 410-11 and 410-15 (coupled to a same horizontal accessline and vertical sense lines 403-3 and 403-7, respectively), and 410-12and 410-16 (coupled to a same horizontal access line and vertical senselines 403-4 and 403-8, respectively). Similarly, a tier 430-P caninclude 410-Q and 410-(Q+4) (coupled to a same horizontal access lineand vertical sense lines 403-1 and 403-5, respectively), 410-(Q+1) and410-(Q+5) (coupled to a same horizontal access line and vertical senselines 403-2 and 403-6, respectively), 410-(Q+2) and 410-(Q+6) (coupledto a same horizontal access line and vertical sense lines 403-3 and403-7, respectively), and 410-(Q+3) and 410-(Q+7) (coupled to a samehorizontal access line and vertical sense lines 403-4 and 403-8,respectively), as illustrated in FIG. 4. Further, each tier 430intersects a plurality of vertical sense lines 403, which run in thethird direction 411 (D3).

As further illustrated in FIG. 4, the vertical sense lines 403-1 to403-4 are coupled to a respective one of a pair of horizontal senselines 422-1 and 422-2 via a respective multiplexor 432-1 to 432-4 thatare formed under the array of vertically stacked memory cells. Forexample, as illustrated in FIG. 4, the vertical sense lines 403-1 and403-3 are coupled to the horizontal sense line 422-1 via multiplexors432-1 and 432-3, respectively, and the vertical sense lines 403-2 and403-4 are coupled to the horizontal sense line 422-2 via multiplexors432-2 and 432-4, respectively. As illustrated in connection with FIG. 4,vertical sense lines 403 include alternating vertical sense lines alongthe pair of horizontal sense lines 422.

The multiplexor 432-1 can operate to electrically couple/decouple thevertical sense line 403-1 to/from the horizontal sense line 422-1 (suchthat one of the memory cells 410-1, 410-9, and 410-Q can be accessed);the multiplexor 432-2 can operate to electrically couple/decouple thevertical sense line 403-2 to/from the horizontal sense line 422-2 (suchthat one of the memory cells 410-2, 410-10, and 410-(Q+1) can beaccessed); the multiplexor 432-3 can operate to electricallycouple/decouple the vertical sense line 403-3 to/from the horizontalsense line 422-1 (such that one of the memory cells 410-3, 410-11, and410-(Q+2) can be accessed); and the multiplexor 432-4 can operate toelectrically couple/decouple the vertical sense line 403-4 to/from thehorizontal sense line 422-2 (such that one of the memory cells 410-4,410-12, and 410-(Q+3) can be accessed).

As described herein, each multiplexor can operate to electricallycouple/decouple a vertical sense line to/from a respective horizontalsense line. Although not shown in FIG. 4, a pair of horizontal senselines 422-1 and 422-2 can be coupled to a sense amplifier (e.g., thesense amplifier 326 illustrated in FIG. 3). To sense a memory cell, thecontrol circuitry (e.g., the control circuitry 652 illustrated in FIG.6) can cause two multiplexers that are adjacent to each other andcoupled to a pair of horizontal sense lines 422 to electrically coupleone vertical sense line (to which the memory cell to be sensed iscoupled) to one of the pair of horizontal sense lines and anothervertical sense line to a different one of the pair of horizontal senselines. For example, to sense the memory cell 410-1, the controlcircuitry can cause the multiplexor 432-1 to electrically couple thevertical sense line 403-1 to the horizontal sense line 422-1 and causethe multiplexor 432-2 to electrically couple the vertical sense line403-2 to the horizontal sense line 422-1, while causing remainingmultiplexors 432-3 and 432-4 to decouple remaining vertical sense lines(e.g., vertical sense lines 403-3 and 403-4) from respective horizontalsense lines 422-1 and 422-2. The control circuitry can further activatean access line driver (e.g., the access line driver 228 illustrated inconnection with FIG. 2) to provide a positive power supply to thehorizontal access line 407-1, which will further provide a differentialvoltage (e.g., a voltage difference between the vertical sense lines403-1 and 403-2) to the sense amplifier via horizontal sense lines 422-1and 422-2.

FIG. 5 is a schematic illustration of a vertical sense line multiplexor532 in accordance a number of embodiments of the present disclosure. Themultiplexor 532 can be formed under an array of memory cells comprisinga plurality of vertically stacked tiers of memory cells, such as isillustrated in FIG. 4. The array can include a plurality of verticalsense lines, such as the vertical sense line 403 illustrated in FIG. 4,coupled to the tiers of memory cells. Each vertical sense line can becoupled to a respective multiplexor. For a group of vertical senselines, the respective multiplexors function to select and/or deselect(electrically couple/decouple) the vertical sense lines to/from ahorizontal sense line, such as the horizontal sense line 422 illustratedin FIG. 4.

The multiplexor 532 can include a first transistor 549-1 and a secondtransistor 549-2. The first transistor 549-1 can have a first terminal545-1 coupled to a vertical sense line 503 and to a first terminal 545-2of the second transistor 549-2. The first transistor 549-1 can have asecond terminal 525-1 coupled to a horizontal sense line 522. The secondtransistor 549-2 can have a second terminal 525-2 coupled to a verticalchannel 547 (e.g., “DVC2”).

The multiplexor 532 can be configured such that deactivation of thefirst transistor 549-1 and activation of the second transistor 549-2causes the respective vertical sense line 503 to be electrically coupledto the vertical channel 547. To deactivate either the first transistor549-1 or the second transistor 549-2, a first signal (“Vss”) can beapplied to a gate 541-1 of the first transistor 549-1 or to a gate 541-2of the second transistor 549-2. To activate the first transistor 549-1,a second signal (“VEQ”) can be applied to a gate 541-1 of the firsttransistor 549-1. To activate the second transistor 549-2, a thirdsignal (“Vdd”) can be applied to a gate 541-2 of the second transistor549-2. The multiplexor 532 can be configured such that activation of thefirst transistor 549-1 and deactivation of the second transistor 549-2causes the respective vertical sense line 503 to be electrically coupledto the horizontal sense line 522.

In at least one embodiment, both the first transistor 549-1 and thesecond transistor 549-2 comprise n-type metal oxide semiconductor (nMOS)transistors. The multiplexors 532 can be formed as semiconductor underthe array circuitry, which is sometimes referred to as complimentarymetal oxide semiconductor (cMOS) under the array (CuA) circuitry.However, for embodiments in which both transistors of the multiplexor532 are nMOS transistors, the circuitry can be referred to as nMOS underthe array circuitry. The multiplexor 532, formed as nMOS under the arraytakes less space than if the multiplexor 532 was formed as cMOS underthe array. According to at least one embodiment of the presentdisclosure, the multiplexors 532 formed as nMOS under the array, areable to fit directly under respective vertical sense lines 503 such thateach vertical sense line 503 in the array can have an nMOS multiplexor532 formed thereunder without sacrificing space that would otherwise berequired if cMOS multiplexors were used. The use of cMOS multiplexorswould not be feasible for given feature widths in current fabricationprocesses because the cMOS multiplexors could not fit within the givendimensions.

FIG. 6 is a block diagram of an apparatus in accordance with a number ofembodiments of the present disclosure. FIG. 6 is a block diagram of anapparatus in the form of a computing system 650 including a memorydevice 651 in accordance with a number of embodiments of the presentdisclosure. As used herein, a memory device 651, a memory array 653,and/or a host 602, for example, might also be separately considered an“apparatus.” According to embodiments, the memory device 602 maycomprise at least one memory array 653 with a memory cell formed havinga digit line and body contact, according to the embodiments describedherein.

In this example, system 650 includes a host 602 coupled to memory device651 via an interface 654. The interface 654 can pass control, address,data, and other signals between the memory device 651 and the host 602.The interface can include a command bus (e.g., coupled to the controlcircuitry 652), an address bus (e.g., coupled to the address circuitry606), and a data bus (e.g., coupled to the input/output (I/O) circuitry657. In some embodiments, the command bus and the address bus can becomprised of a common command/address bus. In some embodiments, thecommand bus, the address bus, and the data bus can be part of a commonbus. The command bus can pass signals between the host 602 and thecontrol circuitry 652 such as clock signals for timing, reset signals,chip selects, parity information, alerts, etc. The address bus can passsignals between the host 602 and the address circuitry 606 such aslogical addresses of memory banks in the memory array 653 for memoryoperations. The interface 654 can be a physical interface employing asuitable protocol. Such a protocol may be custom or proprietary, or theinterface may employ a standardized protocol, such as PeripheralComponent Interconnect Express (PCIe), Gen-Z interconnect, cachecoherent interconnect for accelerators (CCIX), etc. In some cases, thecontrol circuitry 652 is a register clock driver (RCD), such as RCDemployed on an RDIMM or LRDIMM.

The computing system 650 can be a personal laptop computer, a desktopcomputer, a digital camera, a mobile telephone, a memory card reader, oran Internet-of-Things (IoT) enabled device, among various other types ofsystems. Host 602 can include a number of processing resources (e.g.,one or more processors, microprocessors, or some other type ofcontrolling circuitry) capable of accessing memory 651. The system 650can include separate integrated circuits, or both the host 602 and thememory device 651 can be on the same integrated circuit. For example,the host 602 may be a system controller of a memory system comprisingmultiple memory devices 651, with the system controller 652 providingaccess to the respective memory devices 651 by another processingresource such as a central processing unit (CPU).

In the example shown in FIG. 6, the host 602 is responsible forexecuting an operating system (OS) and/or various applications (e.g.,processes) that can be loaded thereto (e.g., from memory device 651 viacontroller 652). The OS and/or various applications can be loaded fromthe memory device 651 by providing access commands from the host 602 tothe memory device 651 to access the data comprising the OS and/or thevarious applications. The host 602 can also access data utilized by theOS and/or various applications by providing access commands to thememory device 651 to retrieve said data utilized in the execution of theOS and/or the various applications.

For clarity, the system 650 has been simplified to focus on featureswith particular relevance to the present disclosure. The memory array653 can be a DRAM array comprising at least one memory cell having adigit line and body contact formed according to the techniques describedherein. For example, the memory array 653 can be an unshielded DL 4F2array such as a 3D-DRAM memory array. The array 653 can comprise memorycells arranged in rows coupled by access lines (which may be referred toherein as word lines or select lines) and columns coupled by digit lines(which may be referred to herein as sense lines or data lines). Althougha single array 653 is shown in FIG. 6, embodiments are not so limited.For instance, memory device 651 may include a number of arrays 653(e.g., a number of banks of DRAM cells).

The memory device 651 includes address circuitry 606 to latch addresssignals provided over an interface 654. The interface can include, forexample, a physical interface employing a suitable protocol (e.g., adata bus), an address bus, and a command bus, or a combineddata/address/command bus. Such protocol may be custom or proprietary, orthe interface 654 may employ a standardized protocol, such as PeripheralComponent Interconnect Express (PCIe), Gen-Z, CCIX, or the like. Addresssignals are received and decoded by a row decoder 608 and a columndecoder 612 to access the memory array 653. Data can be read from memoryarray 653 by sensing voltage and/or current changes on the sense linesusing sensing circuitry 655. The sensing circuitry 655 can comprise, forexample, sense amplifiers that can read and latch a page (e.g., row) ofdata from the memory array 653. The I/O circuitry 657 can be used forbi-directional data communication with the host 602 over the interface654. The read/write circuitry 613 is used to write data to the memoryarray 653 or read data from the memory array 653. As an example, thecircuitry 613 can comprise various drivers, latch circuitry, etc.

Control circuitry 652 decodes signals provided by the host 602. Thesignals can be commands provided by the host 602. These signals caninclude chip enable signals, write enable signals, and address latchsignals that are used to control operations performed on the memoryarray 653, including data read operations, data write operations, anddata erase operations. In various embodiments, the control circuitry 652is responsible for executing instructions from the host 602. The controlcircuitry 652 can comprise a state machine, a sequencer, and/or someother type of control circuitry, which may be implemented in the form ofhardware, firmware, or software, or any combination of the three. Insome examples, the host 602 can be a controller external to the memorydevice 651. For example, the host 602 can be a memory controller whichis coupled to a processing resource of a computing device.

The term semiconductor can refer to, for example, a material, a wafer,or a substrate, and includes any base semiconductor structure.“Semiconductor” is to be understood as including silicon-on-sapphire(SOS) technology, silicon-on-insulator (SOI) technology,thin-film-transistor (TFT) technology, doped and undoped semiconductors,epitaxial silicon supported by a base semiconductor structure, as wellas other semiconductor structures. Furthermore, when reference is madeto a semiconductor in the preceding description, previous process stepsmay have been utilized to form regions/junctions in the basesemiconductor structure, and the term semiconductor can include theunderlying materials containing such regions/junctions.

It should be recognized the term vertical accounts for variations from“exactly” vertical due to routine manufacturing, measuring, and/orassembly variations and that one of ordinary skill in the art would knowwhat is meant by the term “perpendicular.” For example, the vertical cancorrespond to the z-direction. As used herein, when a particular elementis “adjacent to” an other element, the particular element can cover theother element, can be over the other element or lateral to the otherelement and/or can be in direct physical contact the other element.Lateral to may refer to the horizontal direction (e.g., the y-directionor the x-direction) that may be perpendicular to the z-direction, forexample.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe present disclosure includes other applications in which the abovestructures and methods are used. Therefore, the scope of variousembodiments of the present disclosure should be determined withreference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

What is claimed is:
 1. A memory device, comprising: an array of memorycells comprising: a plurality of vertically stacked tiers of memorycells; and a respective plurality of horizontal access lines coupled toeach of the plurality of tiers; a plurality vertical sense lines coupledto each of the plurality of tiers; semiconductor under the arraycircuitry, comprising a plurality of multiplexors each coupled to arespective vertical sense line and to a respective horizontal senseline; and a plurality of sense amplifiers each coupled to a respectivepair of horizontal sense lines; wherein each of the plurality ofmultiplexors comprises a respective pair of transistors; and wherein therespective pair of transistors is configured such that: activation of afirst of the respective pair of transistors causes the respectivevertical sense line to be electrically coupled to the respectivehorizontal sense line; and activation of a second of the respective pairof transistors causes the respective vertical sense line to beelectrically decoupled from the respective horizontal sense line.
 2. Thememory device of claim 1, wherein: a first horizontal sense line of therespective pair is coupled to a first subset of the plurality ofvertical sense lines via a first subset of the plurality ofmultiplexors; and a second horizontal sense line of the respective pairis coupled to a second subset of the plurality of vertical sense linesvia a second subset of the plurality of multiplexors.
 3. The memorydevice of claim 2, wherein the first and the second subsets of verticalsense lines comprise alternating vertical sense lines along the pair ofhorizontal sense lines.
 4. The memory device of claim 1, wherein: eachof the plurality of vertical sense lines is coupled to a differentmemory cell in each of the plurality of tiers; and the plurality ofsense amplifiers comprise differential sense amplifiers.
 5. The memorydevice of claim 1, wherein each of the plurality of multiplexorscomprises n-type metal oxide semiconductor (nMOS) transistor.
 6. Thememory device of claim 1, wherein the plurality of sense amplifiers arehorizontally adjacent to the array of memory cells.
 7. A memory device,comprising: an array memory cells comprising a plurality of verticallystacked tiers of memory cells coupled to a plurality of horizontalaccess lines and to a plurality of vertical sense lines; semiconductorcircuitry formed under the array comprising: a plurality of multiplexorsformed under the plurality of vertically stacked tiers of memory cells,each one of the plurality of multiplexors coupled to a respective one ofthe plurality of vertical sense lines; and a plurality of pairs ofhorizontal sense lines coupled to the plurality of multiplexors;semiconductor circuitry formed outside of the array comprising aplurality of sense amplifiers each coupled to a respective one of theplurality of pairs of horizontal sense lines; and control circuitryconfigured to cause, to sense memory cells coupled to a first horizontalaccess line of the plurality of horizontal access lines, a first portionof the plurality of multiplexors to electrically couple a first portionof the plurality of vertical sense lines to a first one of each pair ofthe plurality of pairs of horizontal sense lines, wherein the firstportion of the plurality of vertical sense lines is coupled to the firsthorizontal access line of the plurality of horizontal access line;wherein each of the plurality of multiplexors comprises a respectivepair of transistors; and wherein the respective pair of transistors isconfigured such that: activation of a first of the respective pair oftransistors causes the respective vertical sense line to be electricallycoupled to the respective horizontal sense line; and activation of asecond of the respective pair of transistors causes the respectivevertical sense line to be electrically decoupled from the respectivehorizontal sense line.
 8. The memory device of claim 7, wherein thecontrol circuitry is configured to cause a second portion of theplurality of multiplexors to electrically decouple a second portion ofthe plurality of vertical sense lines from the first one of each pair ofthe plurality of pairs of horizontal sense lines, wherein the secondportion of the plurality of vertical sense lines is not coupled to thefirst horizontal access line of the plurality of horizontal access line.9. The memory device of claim 7, wherein: a second portion of theplurality of vertical sense lines to a second one of each pair of theplurality of pairs of horizontal sense lines; and the control circuitryis configured to cause the second portion of the plurality ofmultiplexors to electrically couple the second portion of the pluralityof vertical sense lines to a second one of each pair of the plurality ofpairs of horizontal sense lines, wherein: each one of the second portionof the plurality of vertical sense lines is located adjacent to arespective one of the first portion of the plurality of vertical senselines, respectively; and the second portion of the plurality of verticalsense lines is not coupled to the first horizontal sense line of theplurality of horizontal sense line.
 10. The memory device of claim 9,wherein: a third portion of the plurality of multiplexors is coupled tothe second one of each pair of the plurality of pairs of horizontalsense lines and a remaining portion of the plurality of vertical senselines; and the control circuitry is configured to cause the thirdportion of the plurality of multiplexors to electrically decouple theremaining portion of the plurality of vertical sense lines from thesecond one of each pair of the plurality of pairs of horizontal senselines.
 11. The memory device of claim 7, wherein: each one of theplurality of horizontal sense lines is coupled to a respective one of aplurality of access line drivers; and the control circuitry isconfigured to activate, to sense the memory cells, a first one of theplurality of access line drivers coupled to the first horizontal senseline.
 12. The memory device of claim 11, wherein the control circuitryis configured to deactivate a remaining one of the plurality of accessline drivers that is not coupled to the first horizontal sense line. 13.The memory device of claim 7, wherein a first portion of the pluralityof multiplexors is coupled to the first one of each pair of theplurality of pairs of horizontal sense lines and a second portion of theplurality of multiplexors is coupled to a second one of each pair of theplurality of pairs of horizontal sense lines.
 14. The memory device ofclaim 7, wherein a first portion of the plurality of sense amplifiers iscoupled to a first end of the plurality of pairs of horizontal senselines and a second portion of the plurality of sense amplifiers iscoupled to a second end of the plurality of pairs of horizontal senselines that is opposite to the first end.
 15. The memory device of claim7, wherein a first portion of a plurality of sub-access line drivers iscoupled to a first end of the plurality of horizontal access lines and asecond portion of the plurality of sub-access line drivers is coupled toa second end of the plurality of horizontal access lines that isopposite to the first end.
 16. A method of sensing a memory cell in anarray, comprising: among a respective plurality of horizontal accesslines coupled to each of a plurality of vertically stacked tiers ofmemory cells, activating a particular horizontal access line coupled tothe memory cell; electrically coupling a first vertical sense line to afirst horizontal sense line via a first multiplexor in semiconductorunder the array circuitry, wherein the first vertical sense line iscoupled to the memory cell; electrically coupling a second verticalsense line to a second horizontal sense line via a second multiplexor inthe circuitry, wherein the second vertical sense line is not coupled tothe memory cell; and sensing the memory cell with a differential senseamplifier coupled to the first horizontal sense line and the secondhorizontal sense line, wherein the differential sense amplifier ishorizontally adjacent to the plurality of vertically stacked tiers ofmemory cells; wherein each of the first and second multiplexorscomprises a respective pair of transistors; and wherein the respectivepair of transistors is configured such that: activation of a first ofthe respective pair of transistors causes the respective vertical senseline to be electrically coupled to the respective horizontal sense line;and activation of a second of the respective pair of transistors causesthe respective vertical sense line to be electrically decoupled from therespective horizontal sense line.
 17. The method of claim 16, furthercomprising: activating an access line driver coupled to the firsthorizontal sense line; and deactivating an access line driver coupled tothe second horizontal sense line.
 18. The method of claim 16, furthercomprising, prior to sensing the memory cell: electrically decoupling atleast one other vertical sense line from the first horizontal senseline; and electrically decoupling at least one other vertical sense linefrom the second horizontal sense line.
 19. The method of claim 16,wherein electrically coupling the first vertical sense line to the firsthorizontal sense line via the first multiplexor comprises applying asignal to a gate of a first transistor of a pair of transistorscomprising the first multiplexor.